Interleukin 4 receptor: signaling mechanisms.

Achsah Keegan and colleagues consider the signaling mechanisms utilized by the interleukin 4 (IL-4) receptor and review evidence suggesting that these mechanisms can account for the known responses of hematopoietic and non-hematopoietic cells to IL-4. Most of these data have been obtained from analyses of the ability of IL-4 to regulate the growth of IL-3-dependent myeloid cell lines. These results have implicated a pathway of activation homologous to that utilized by insulin and insulin-like growth factor 1 (IGF-1). However, it is possible that the regulation of growth responses through the IL-4 receptor (and other receptors), and the differentiative events elicited in lymphocytes, may not be mediated by the same post-receptor events.